Mix the clay, silica and water to form the slurry. Fill the mold with the slurry until it is full. It takes 20 kilos of slurry to make one toilet. Allow the mold to set for one hour. The gypsum will help to absorb some of the water from the slurry. Pull the plug from the mold and allow the excess slurry to flow out into a bucket.
Unmold the toilet, which will be in two pieces. You must do this carefully to keep from damaging the toilet because it still is wet and fragile. Pour a layer of wet slurry between the two pieces of the toilet and then put them together. Use a knife or similar tool to cut the opening into the toilet for the plumbing fixtures.
Remove the excess slurry from around the edges of the bowl using a knife or similar tool. A cheese slicer works great for this, since you want to remove the excess without damaging the still wet bowl. Allow the toilet to air dry for at least 36 hours before moving on to the next step.
Allow the toilet to dry in a warm air dryer for about 12 hours. Sand the toilet so that it is completely smooth after you remove it from the warm air dryer. Blow away excess dust with an air compressor. Paint the toilet and allow it to dry properly for at least 24 hours.
Glaze the toilet using a heat-resistant glaze after the paint dries and allow it to dry for several hours. Dry the toilet in a kiln. Ceramic will break if it gets too hot, too fast so the process must be gradual until the kiln is at 1,176 degrees. Gradually drop the temperature to prevent cracking the bowl. The total processing time in the kiln is 23 hours.
Allow the toilet to cool completely for about 24 hours and then install the hardware on the toilet tank. The toilet now is ready to install in the bathroom.